The Internet has become a cultural medium to send and receive various kinds of visual, audiovisual or other type of multimedia information. By using a WWW browser software, it is possible to have instantly access to Internet sites around the world through the Internet which provide various kinds of information contents and services to browse such contents and send data to Internet sites. In addition, data, mail or message can be immediately exchanged with many people around the world through the Internet. The Internet has become widely used at office, school and home recently.
Various kinds of information, contents and services, such as shopping, news service, retrieval of information like library, delivery of music, and trading stocks, are provided through the Internet today. Therefore, more and more offices, schools, and homes are being connected to the Internet, which changes business, education, and our daily life significantly.
On the other hand, there is no border control in the Internet. Any one can open his or her own home page in the Internet to provide any kind of information to the public. There are little law and regulations which governs and are well enforced in the cyberspace, the Internet. Therefore, there could be some Internet sites which provide injurious contents, such as contents of pornography, violence or inducing illicit conducts which are harmful or too much sensational to children and juvenile. However, everyone can have access to any Internet sites by using a WWW browser software at school, office or home. On the other hand, there are Internet sites providing contents or services which are not harmful but have nothing to do with work at office. Employees might spend time at office to browse these Internet site just for fun, which could deteriorate work performance and could jam data communication line by unnecessary data traffic on the line at office.
Therefore, as Internet connection to office, school and home has become common, it is necessary to provide a method and apparatus for controlling user's access to the Internet so as to prohibit unsuitable information from entering into office, school or home and ensuring that only appropriate information can be browsed and used by users through the Internet. That is, a method or apparatus for filtering and screening out information or contents from the Internet which is harmful or inappropriate to users is required.
Prior art method and apparatus are disclosed by Japanese published unexamined patent application 10-275157 and “Companies Start Controlling Internet Access, Second Part, Software For Monitoring And Controlling Internet Access”, Nikkei Computer, pp.87-91, 1999.5.10. The prior art apparatus or method includes a means or step for checking for predetermined harmful keywords in information or contents from the Internet before the information or contents are displayed on a display screen at a client computer. If the information or contents include the predetermined harmful keywords, the display of the information or contents at a client computer is prohibited and the Uniform Resource Locator (URL) of the Internet site which sent the information or contents to the client computer is recorded for prohibiting client's future access. Japanese Patent No. 2951307 discloses a system which checks for harmful or defamation words in a message to be displayed in a bulletin board in an Internet site or other computer network system and if there is such a word in a message, the display of the message on a bulletin board is rejected by the system.
However, there is a problem in prior art, that is, it takes time to look for harmful, injurious, or defamation keywords in information or contents from Internet sites each time before displaying the information or contents on a display screen at a computer. Moreover, there is another problem in prior art, that is, once such a keyword is found, the display of the information or contents including such a keyword is prohibited. However, it does not necessarily mean that information or contents including harmful, injurious, or defamation keywords are always harmful, injurious, or defamation by themselves. For example, news articles from Internet sites operated by news agency which report crime sometimes include harmful keywords, such as “murder” etc. But, news article reporting such a crime is not harmful per se and it may not need to prohibit news article reporting crime from Internet sites operated by news agencies from being displayed on a display screen on a client computer. Prior art apparatus or software sometimes prohibit even useful information or contents from Internet sites from being displayed on a display screen just because of the existence of forbidden keywords.